The fabrication of nanometer-size electronic circuits with a high density of elements, high operational speed, and low manufacturing cost promises wide applications in future electronic devices. However, a major problem for nanoelectronics is to develop methods to fabricate an interface between nanowires and external microwires. Such interfaces are needed to efficiently input/output electrical signals from the external circuitry into the nanowires, selectively supply and distribute power, and provide internal interconnects between the nanowires. In conventional microelectronics, these problems are solved by means of selective interconnections of the electronic elements. An example is the multiplexer/demultiplexer interface shown in FIG. 1 and described in detail below. At the nanoscale, such interfaces require selective connection or disconnection between the nanowire and microwire at each cross point. As a result, the feature size along the microwire has to be comparable with the width of the nanowire and with the spacing between them, so it has to be of nanoscale itself. This is impossible to achieve by conventional photolithographic means with current mechanical accuracy for positioning one set of features over another.
One example of such interconnections between nanowires and microwires is disclosed in U.S. Pat. No. 6,256,767, entitled “Demultiplexer for a Molecular Wire Crossbar Network (MWCN Demux)”, issued to Philip J. Kuekes et al on Jul. 3, 2001, and assigned to the same assignee as the present application, the contents of which are incorporated herein by reference. That patent discloses a randomly patterned demultiplexer for a two-dimensional array of a plurality of nanometer-scale switches (a molecular wire crossbar network), employing a bistable molecule as a connector species connecting pairs of crossed wires at each junction in the crossbar network. The present application is an improvement thereover in that, as disclosed and claimed herein, a method of fabricating a predetermined pattern of nanowire-microwire connections is provided, thereby reducing the number of microwires required and reducing the area occupied by the multiplexer/demultiplexer.
A need remains for a method of making arbitrary connections from specific microwires to specific nanowires.